1. Field of the Invention
The present invention generally relates to a heat sink applied to an integrated circuit, and more particularly to a package device with a heat sink to reduce the thermal resistance and to improve the efficiency of thermal dissipation.
2. Description of the Prior Art
In the electronics and computer industries, it has been well known to employ various types of electronic package devices and integrated circuit chips, such as the PENTIUM central processing unit chip (CPU) manufactured by Intel Corporation. These integrated circuit chips have a pin grid array (PGA) package and are typically installed into a socket. These integrated circuit chips are installed onto a computer circuit board by soldering. These integrated circuit device for example the CPU microprocessor chips, generate a great deal of heat during operation which must be removed to prevent adverse effects. The PENTIUM microprocessor contain millions of transistors, and they are highly susceptible to overheating. Therefore, the microprocessor device itself or other components proximal to the microprocessor are easy to be destroyed because of overheating.
In addition to the above discussion, there are many other types of semiconductor package devices, which are commonly used in computer equipment. At least some of these semiconductor package devices also have the above-mentioned problem. For example, the resistors and thermistors generate large volumes of heat during normal operation, and if the heat can not be dissipated quickly to cool down the resistors and thermistors they can be destroyed and damaged by the heat.
Also, the solid-state devices are commonly being installed onto a circuit board, or be installed into a motherboard or other similar primary circuit board in turn. For example, microprocessors, such as the PENTIUM II and the Celeron from Intel, are so-called “processor cards” which are installed into a motherboard of a computer in similar fashion to the way a modem is installed into a motherboard. The existing processor card, as known, has the processor semiconductor devices, such cache chips, or the like, and they are necessary for the operation of the card. The processor package may be installed into the processor card via a pin grid, ball grid, and land grid array and with a socket such as a ZIF or ball grid socket.
Similarly, according to the earlier semiconductor devices discussed above, there are many different types of electronic devices which suffer from overheating. For example, any electronic package device may have a threat of overheating, and need to be cooled down to prevent overheating. However, the devices are too small to adequately support and receive the typical metallic heat sink. These prior metallic heat sinks are commonly glued directly to the electronic device with a thermally conductive adhesive, or installed into the electronic package device with a mechanical structure, such as a spring clip. Further, gap pads out the interface surface between the package device and the dissipating structure are often required to achieve thermal dissipating efficiency. In view of the foregoing issues related to these types of electronic components, providing heat dissipation in the form of heat sinks, and the like, is difficult and cost prohibitive.
The foregoing heat sink assembly of the prior art suffers from the disadvantages of having multiple components and the high cost associated therewith. These multiple component heat sink assemblies typically include expensive machined or extruded heat conductive metal, such as aluminum. Other parts, such as springs or addition clips require separate machining steps and/or molds for production. Therefore, these assemblies and methods are completely inappropriate for most electronic devices.
FIG. 1 and FIG. 2 illustrate a conventional ball grid array package 100 with heat slug. The ball grid array package device with heat slug includes a ball grid array substrate 102, a chip or die 104 that is located on the ball grid array substrate 102, and a modified heat slug 106 that is positioned over the chip 104 and the ball grid array substrate 102. Then, a molding compound 108 is injected into the ball grid array package device 100 to accomplish the ball grid array packaging process. Referring to FIG. 2, the die or chip 104 is covered by the molding compound 108, and the heat dissipating path is restricted by the low thermal conductivity of the molding compound 108. So the ball grid array package device 100 can not get good heat dissipating efficiency. The solution of this problem is to add an embedded heat slug 108 onto the die or chip 104 to increase the heat dissipating area. Nevertheless, the defect of this technique is that if the die or chip 104 generate a large volume of heat, the heat cannot be removed to the environment sufficiently to reduce the operating temperature of the die or chip 104. Therefore, the chip or die 104 cannot be operated.